Abstract: A ternary complex with the formula of[Dy(p-MBA)₃phen]₂(p-MBA=p-methylbenzoic acid;phen=1,10-phenathroline) was synthesized via the solution method. Elemental analysis,infrared spectra,molar conductance,thermogravimetry and derivative thermogravimetry(TG-DTG) were used to characterize the title complex.The results show the Dy(Ⅲ) ion was coordinated to the oxygen atoms of p-methylbenzoic acid,and the nitrogen atoms of the 1,10-phenanthroline,and the title complex has a good thermal stability.Nonisothermal kinetics of the first thermal decomposition stage of Dy(Ⅲ) complex was studied in the static air atmosphere.Through the Popescu method and the nonlinear integral isoconversional(NL-INT) method,the kinetic equation was expressed as (dα)/(dT)=(15.55 × 10¹²)/(β) exp ((-19825.60)/(T))3(1-α)^2/3, and the average activation energy and the pre-exponential factor were 164.83 kJ/mol and 15.55 × 10¹² min^-1,respectively.The thermal stability of a series of complexes was compared. The results may provide some valuable materials for the choice of functional materials of rare-earth complexes.